1. Field of the Invention
Exemplary embodiments of the present invention relate to light emitting diodes (LEDs) and, more particularly, to a conversion type light emitting device capable of converting light emitted from an LED into a different kind of light by a movable fluorescent element. More particularly, the present invention relates to a sterilization-lighting conversion type light emitting device that can selectively perform sterilization and lighting by converting ultraviolet light into visible light (particularly, white light), and vice versa.
2. Discussion of the Background
LEDs are a kind of semiconductor diode that emit light based on the principle energy is released in the form of light through recombination of electrons and holes when the diode is biased to allow a current to be injected into the diode in one direction. Generally, an LED element refers to an LED chip or LED package in which the LED chip is sealed in a package.
The LEDs emit light having a single peak wavelength, which is determined according to a semiconductor crystal material, kind, and concentration of impurities in a p-n junction, structure, and the like. The LEDs are classified into a blue LED, a green LED, a red LED, an ultraviolet (UV) LED, and the like according to peak wavelengths.
Since the LED emits monochromatic light, it is necessary to mix light having different peak wavelengths in order to obtain a desired color, such as, white light. To this end, a technique has been developed to mix light having different peak wavelengths emitted from different kinds of LEDs.
Further, a technique has been developed to emit a desired color through color mixture between non-wavelength-converted light and wavelength-converted light using phosphors converting the wavelength of light emitted from one LED. As well known in the art, for example, white light can be obtained by combination of a blue LED and green and red phosphors or combination of the blue LED and yellow phosphors. Further, white light can also be obtained by a combination of a UV LED and blue, green, and yellow phosphors or combination of the UV LED and blue and yellow phosphors.
Since such conventional techniques provides fixed light via combination of the LED and the phosphors, it is difficult to use characteristic light that is emitted from the LED and does not pass through the phosphors. Particularly, the UV LED emits UV light exhibiting excellent sterilization properties, but the combination of the UV LED and phosphors eliminates such sterilization properties. As a result, the application of the conventional techniques to systems, equipment or apparatuses demanding both a lighting function of visible light (particularly, white light) and a sterilization function is inefficient.